Biodiversity and Conservation Class 12 Notes Biology Chapter 15 - CBSE 


What are Biodiversity and Conservation?

Forms of Biodiversity

Genetic diversity

  • (diversity at the genetic level)

Species diversity

  • (diversity at the species level)

Genetic diversity

  • (diversity at the genetic level)

According to IUCN:

Robert May- Global species biodiversity is about 7 million. 70% are animals among animals, 61% are insect species. 22% are plants.

Patterns Of Biodiversity

  • Biodiversity is not uniform throughout the world but varies with latitude and altitude.

Latitudinal Gradients

  • Species diversity decreases from equator towards poles.
  • Amazon Rainforest has the greatest biodiversity on Earth.

Reasons For Biodiversity In Tropical Areas

  • Tropical latitudes were undisturbed over a long period of time which resulted in speciation and evolution.
  • Less seasonal variations.

Species-area Relationship

  • Alexander Von Humboldt - species richness increases with the increase of explored area but only up to a certain limit.
  • The relationship between species richness and area is found to be a rectangular hyperbola.

Graph Showing Species-area Relationship

  • The equation is described by – log S = log C + Z log A
  • S – Species Richness
  • Z – Slope of the line (regression coefficient)
  • A – Area
  • C – y-intercept
  • Value of Z -0.1 to 0.2
  • For continents, Z value ranges between 0.6 to 1.2.

Importance Of Biodiversity

There is no exact answer to this question, but experiments conducted by many ecologists have demonstrated that a system with greater biodiversity is more stable and has greater productivity.

Loss Of Biodiversity

Loss of Biodiversity is the loss of genetic variability, variety of species, and the biological communities in a given area. Some of the causes of this loss are:

  • Habitat loss and fragmentation
  • Over-exploitation
  • Alien-species invasion
  • Co-extinction
  • According to The IUCN Red List (2004) 784 species are extinct (including 338 Vertebrates, 359 invertebrates and 87 plants) in the last 500 years.

Biodiversity Conservation

Biodiversity is responsible for balancing the ecosystem, cleans the air and water, supply oxygen etc.

Biodiversity Conservation

  • In situ
  • Protected Area Network
  • Sacred Groves, Sacred Lakes
  • Biosphere Reserves
  • ➥ Terrestrial
  • ➥ Marine
  • National Parks, Wildlife Sanctuaries
  • Ex situ
  • Home Gardens
  • Seed Banks, gene Banks, Cryopreservation
  • Botanical Gardens, Zoological Gardens, Aquarium
  • Sacred groves: These are the protected areas which are considered as religiously important and activities such as hunting etc are prohibited in the areas.
  • Biosphere reserves: It is a large protected area for the conservation of biodiversity.
  • National Park: National parks are the protected areas for the conservation of nature and natural resources.
  • Hotspot: A biogeographical region with significant levels of biodiversity that is threatened by human habitation.
  • Endangered organisms: A species that is very likely to become extinct shortly, either worldwide or in a particular political jurisdiction
  • Red data book: Book (published by IUCN) contains a record of animals and plants which are known to be in danger.
  • Ramsar sites: The Ramsar sites, an international body forms the basis for the identification of wetlands.